This can have to do with the quality of the cable / cable plant inside the home. I've had this happen for channels that are using frequencies at or near the upper end of bandwidth spectrum to the point of having a particular box seeing so much interference that the box is unable to decode some channels at all. This can be particularly true if you live near any sources of high levels of RF (such as a radio tower or high power lines).
Improving the cable plant quality and reducing the amount of noise leakage into the system can help resolve the issue. You can do this by trying a few things:
1. Make the distance between any cable boxes and the ONT as short as possible.
2. Use high quality shielded cable (not those cheap push on cables you often get "in the box" with some electronics or ones with suspect shielding).
3. Remove any unnecessary splitters. Disconnect cable runs going to outlets you aren't actively using.
4. For any splitters you do have, make sure they are high quality digital cable splitters (5-5000mhz typically rated). And make sure there are no "FM" interference filters installed anywhere -- as these filter frequencies right near the top of the TV spectrum, they can clip signals they shouldn't.
5. For any outlets you can't disconnect but which don't have a device actually connected to it, purchase an install a "terminator" (they can be cheaply obtained from Amazon or another online retailer and often come in packs of 5 or more). This will "seal" off one of the primary points of entry of electronic noise into your cable plant.
6. Remove any "amplifiers" or other signal boosters. FiOS and signal boosters don't mix as the technology being used is not compatible with typical "amplifiers" which are meant for traditional "cable" company networks (MoCA vs DOCSIS).
6. Make sure you're using a good quality HDMI cable. although typically, if this is the issue, you will experience issues on all channels, not just one or two.
If you want to test if this might be the source of your issue, take a cable box, your router, and a TV and temporarily set it up right next to your ONT and directly cable to the ONT (disconnecting all other coax and splitters except for the one you need to hook up the cable box and router) and see if you get better results. If so, noise is your likely culprit.